1. Field of the Invention
The present invention relates to a multi-anode type photomultiplier tube and a radiation detector that employs the multi-anode type photomultiplier tube.
2. Description of the Related Art
Japanese unexamined patent application publication No. 05-93781 discloses a radiation detector 200 shown in FIG. 1. This radiation detector 200 includes a scintillator matrix 201 and a multi-anode type photomultiplier tube 203.
The scintillator matrix 201 includes a plurality of scintillators 202 that are arranged in a two-dimensional matrix manner. The scintillator matrix 201 generates and emits scintillation light in accordance with incident radiation. The multi-anode type photomultiplier tube 203 includes a plurality of anode electrodes, and detects scintillation light emitted from the scintillator matrix 201 by outputting output signals from the plurality of anode electrodes. By calculating a center of mass on the output signals from the anode electrodes, it is possible to identify which scintillator has emitted scintillation light.
Japanese unexamined patent application publication No. 11-250853 discloses a multi-anode type photomultiplier tube that is used for a radiation detector. This multi-anode type photomultiplier tube includes a faceplate and a quadrangular prismatic hollow side tube, both of which are made of glass. The side tube is connected to one surface of the faceplate, and extends along a tube axis that is substantially perpendicular to the faceplate. A photocathode is formed on the surface of the faceplate that is connected to the side tube. The photocathode is formed on the surface of the faceplate at its area that is located inside the side tube. The photocathode is for emitting photoelectrons in response to light incident on the faceplate. A plurality of electron multiplying units are provided inside the side tube in one-to-one correspondence with a plurality of regions defined on the photocathode. A plurality of anode electrodes are provided inside the side tube in one-to-one correspondence with the plurality of electron multiplying units.
Japanese unexamined patent application publication No. 03-173056 discloses a division-type photomultiplier tube. The photomultiplier tube has a side tube, which includes a quadrangular prismatic hollow tube head having a relatively large cross-sectional size and a quadrangular prismatic hollow tube main body having a relatively small cross-sectional size. The tube head is connected to one surface of a faceplate. A single anode electrode is provided inside the tube main body.